1. Field of the Invention
This invention relates to scrap metal compacting machines and, in particular but not by way of limitation, to machines used for crushing scrap automobiles.
2. Brief Description of the Prior Art
In the twentieth century the American people have become a nation on wheels; it is not uncommon for a family to own two or even three or four automobiles. To supply the demand for automobiles in the U.S., millions of automobiles are manufactured domestically each year and many more are imported from abroad.
Although, with proper care, an automobile may provide years of service to its owner or, as is often the case, to a succession of owners, eventually its useful life as a means of transportation comes to an end, with the result that a large number of automobiles are removed from such service each year. The value of the automobile, however, does not terminate with the end of its use as a moving vehicle. These automobiles form a valuable resource consisting of many tons of scrap steel which are annually available for reprocessing into new commodities.
Clearly, any factor which increases the cost of handling these automobiles reduces their value as a source of steel and, accordingly, reduces the price a scrap dealer can obtain for them. Excessive bulk is such a factor. For example, since the capacity of a carrier, such as a railway car, is limited to the bulk it can accommodate, excessive bulk increases transport costs by reducing the effective weight carrying capacity of the transport means. For this reason, scrap automobiles, which occupy a much larger volume than that of the steel of which they are made, are commonly compacted prior to shipment to a steel mill.
Machines for compacting scrap automobiles are well known in the art. A basic design for these machines is a fixed base and one or more pressing members which are moved to allow an automobile to be placed on the base and subsequently moved down on the automobile to crush it against the base. An example of such a machine is disclosed in U.S. Pat. No. 3,370,078, granted May 1, 1973 to Robert L. Flanagan. In this machine a bin is formed in the base, and a pressing member, a lid, is pivotally mounted on a wall of the bin. A hydraulic ram mounted on the lid raises the lid out of the bin so that an automobile may be placed therein. The hydraulic ram then brings the lid down upon the automobile to crush it.
A problem associated with machines used for this purpose is that the resistance of the automobile to compaction increases near the end of the compaction process. During the initial portion of the process, sheet metal forming an open shell is crumpled so that relatively small forces are required during this part of the process. Near the end of the process, however, the various portions of the automobile being compacted contact and support each other and are supported by the automobile frame so that the crushing force must be increased.
If, as is often the case, the machine uses a hydraulic ram to drive the pressing member, the ram must be capable of providing the large forces required during the final portion of the process. As a result, the full capabilities of the ram may not be utilized during the initial part of the process. Ideally, the machine should be designed such that the full capability of the ram is used during the entire process with this capability being utilized, during the initial portion of the process, to move the pressing member at relatively high speed and, during the final portion of the process, to move the pressing member at a lower speed but with a correspondingly greater force.
Another problem with machines of this type is that the crushed automobile tends to buckle outward during the compaction process. Although this buckling may be prevented by providing the machine with walls, so that the crushing occurs within a chamber, such a solution is not desirable because of the limitations it places on access to the region in which the automobile is crushed.